Study On Dust Of Chinese Parasol Tree Explosion Characteristics And Classification Of Dust Explosion Hazard

There is a serious dust explosion risk in the wood processing industry.Preparation of the ingredients,materials,processing,molding and processing stages are a large number of associated dust produced.Phoenix tree is one of the lightest wood,and it is impervious to moisture.It is rarely seen as a gem of high-grade wood.It is used to make musical instruments,bed boards and wardrobes in the domestic furniture market.Nanjing area is the main planting area of Chinese parasol tree.The raw material of a lots of local wood processing enterprises is the Chinese parasol tree.In this paper,the dust of Chinese parasol tree is taken as the research object,and some parameters of its explosion characteristics are studied in depth.In this paper,dust of Chinese parasol tree is research object,some characteristic parameters of explosion are studied.Hartmann tube,dust layer ignition temperature device,dust cloud ignition temperature device as well as 20L spherical explosion test device are used in this paper.First,single factor test method is used to study concentration of dust,particle size,ignition delay time,injection pressure as well as ignition energy exerting effects on some characteristic parameters of dust explosion,the related mechanism has been reasonably explained.Box-Behnken experiment design of response surface methodology are used to study three factors(concentration of dust,particle size and ignition energy)exerting effect on explosion pressure,and fitting the regression equation,accurate prediction of explosion pressure is carried out by using regression equation.Seven kinds of dust explosion characteristic parameters from 27 kinds of materials are collected,cluster analysis and discriminant analysis of multivariate statistics are used to divide these substances into four categories,the discriminant equations are constructed by these known categories.Specific conclusions are as follows:(1)The minimum ignition energy of the dust is 70mJ,90mJ and 120mJ respectively for dust particle size of(50?75)?m?(37.5?50)?m and(30?37.5)pm respectively.With the increase of dust concentration,the minimum ignition energy shows the law of decreasing first and then increasing.The minimum ignition energy is also affected by ignition delay time and injection pressure.The minimum ignition energy decreases first and then increases with the increase of ignition delay,and the optimum ignition delay is 90ms.The minimum ignition energy increases with the increase of powder injection pressure,then decreases and then increases,and the optimum injection pressure is 0.8MPa.(2)The minimum ignition temperature of dust layer decreases with the increase of dust layer thickness,but when the thickness of dust layer is greater than 15mm,the minimum ignition temperature no longer lower.The minimum ignition temperature of dust cloud with the increasing of the concentration of the first decreased and then increased.The minimum ignition temperature of dust cloud of the particle size being(50?75)?m,(37.5?50)?m and(30?37.5)?m samples is 550?,470? and 450? respectively.(3)Limiting explosible concentration of dust cloud of the particle size being(50?75)?m,(37.5?50)?m and(30?37.5)?m samples is 70g·m-3?50g·m-3 and 40g·m-3.The maximum explosion pressure and the maximum explosion index is respectively 0.5841 MPa and 15.1201MPa ·m·s-1 at the dust particle size of(50?75)p.m.The maximum explosion pressure and the maximum explosion index is respectively 0.7219MPa and 18.0631 MPa·m ·s-1 at the dust particle size of(37.5?50)?m.The maximum explosion pressure and the maximum explosion index is respectively 0.7901MPa and22.7454MPa · m ·s-1 at the dust particle size of(30?37.5)?m.Increasing ignition energy results in an explosion of dust cloud pressure.the samples at the dust particle size of(37.5?50)?m were tested by the ignition energy of 2KJ.6KJ and 10KJ.The maximum explosion pressure appear in the dust concentration of 750g · m-3,its values is 0.5621MPa,0.7111 MPa and 0.7799 MPa respectively.According to the classification of dust explosion risk,the explosion risk of Chinese parasol tree dust is level?,it can be considered as having greater explosion risk.(4)The response surface methodology was used to analyze the factors influencing explosion pressure of dust cloud by Design-Expert software based on Box-Behnken design,then fitting regression equation.The influence degree of three factors on explosion pressure is that concentration of dust>ignition energy>particle size.Subsequently,the experimental conditions were optimized,the maximum explosion pressure for dust cloud is 0.7959MPa under optimized conditions(5)The explosion risk of dust in several kinds of materials is classified by SPSS software based on cluster analysis,Categories being as follows High risk,Middle high risk,middle risk,low risk.The discriminant model is summed up from known categories by using discriminant analysis,stearic acid dust and titanium powder were classified by discriminant model.